According to recently evaluated data, the total energy in the Earth's magnetic field is decreasing rapidly (Humphreys, 2002).  This contradicts frequent evolutionist claims that a minor ("non-dipole") part of the field is storing up enough energy to compensate for the large and steady loss of energy from its main ("dipole") part.  Their claims stem from an epic battle between a creationist physicist, Thomas G. Barnes, and an evolutionist geologist, G. Brent Dalrymple.

Field Fisticuffs
Three decades ago, Dr. Barnes (1971) began publicizing a "trade secret" about the earth's magnetic field.  The field's main ("dipole") part has been losing energy rapidly and steadily since it was first measured in the early 19^th century — about 15% in 170 years!  He showed how such a loss was fully consistent with a very reasonable explanation: that the electrical resistance of the earth's core was steadily dissipating the field's energy as heat (Barnes, 1973).  He pointed out that such a rapid energy loss could not continue for more than about ten thousand years, making a powerful case for a young magnetic field, and hence a young earth.

For nearly a decade, evolutionists ignored this argument, hoping it would go away.  Finally, Dalrymple (1983a,b) published several papers intended to quash Barnes' case.  He pointed out that Barnes had ignored strong fluctuations in the field prior to about three millennia ago, and many reversals of the field's direction recorded in the geologic strata.  He implied that the present decline of the field was merely another magnetic reversal in progress.  Barnes (1984) answered by arguing that magnetic reversals and fluctuations had never occurred. 

A Fan Enters the Ring
Although I was rooting for Barnes in the debate, I did not find his arguments about reversals and fluctuations persuasive.  After studying the issue, I concluded that the evidence for past magnetic reversals is very strong (Humphreys, 1988).  To explain them, I generalized Barnes' theory to allow for rapid motions of the electrically conductive fluid in the earth's core.  I proposed that such motions would produce rapid (day-to-day, week-to-week) reversals of the magnetic field during the Genesis flood, and strong fluctuations in the field for several millennia after the flood.  I also predicted evidence that would support my theory (Humphreys, 1986).  Later, two experts in that discipline found such evidence (Coe and Prévot, 1989).

In 1990, I published a more detailed physical model for the reversals, and I showed that the field would lose energy during the reversals and fluctuations even more rapidly than today (Humphreys, 1990).  The loss rates mean that the field is definitely less than tens of thousands of years old, and they are fully consistent with a 6000-year age.  An article in the prestigious journal Nature (Coe et al., 1994) disclosed more evidence for rapid reversals, evidence again confirming my 1986 prediction.

After that, as far as I know, evolutionists stopped using scientific journals to attack the Barnes-Humphreys theory in scientific journals.  Back in 1986, after seeing my paper, Dalrymple did not take the opportunity to be one of its official reviewers, even though his review would have been published verbatim.  I suspect the skeptics wanted to keep the original Barnes version of the theory as a "straw man" for behind-the-scenes attacks, without calling attention to my less-vulnerable version.

Whatever the reason, criticism of the theory retreated to less scientific and less public arenas, such as skeptics' websites.  There the attacks have persisted, mainly centering on another of Dalrymple's claims, involving the "dipole" and "non-dipole" parts of the field.  The next section explains what those parts are, and the following section explains what Dalrymple claimed about them.

Dipole and Non-dipole Fields
The magnetic lines of force in a pure dipole field emerge from and converge toward two regions called "poles" (hence, "di-pole"), north and south.  What makes it a "pure" dipole field is the fact that the lines have the particular shape I have shown.  Several things can produce a pure dipole field shape.  One would be a very small but powerful bar magnet at the center of the sphere.

The earth's magnetic field does not have a purely dipole shape.  In various places it can differ from a dipole field by as much as 10% in direction or intensity.  Geomagnetic specialists describe the deviations mathematically by adding more magnets.  That is, to the pure dipole field of a tiny bar magnet, they might add a small amount of a four-pole ("quadrupole") field, such as a square of four bar magnets would produce.  If that does not quite account for all the deviation, they add a yet smaller "octopole" part, such as a cube of bar magnets would produce.  They can continue the series for as many parts as is feasible.  The sum of all the non-dipole parts is the non-dipole field.

Of course, bar magnets are not the actual sources of the earth's magnetic field.  The real causes are electric currents, most of them in the earth's core.  A roughly six billion ampere doughnut-shaped loop of current, thousands of kilometers in diameter, causes the dipole part.  Smaller loops (hundreds of kilometers in diameter) of smaller currents (thousands to millions of amperes), in all sorts of orientations, are a likely cause of the non-dipole parts of the field.  Another possible cause would be a small displacement (a few hundred kilometers) of the main loop of current northward of the center.

Many different combinations of current loops could produce the field we observe, but the mathematical specification of the magnitude of the sources of the field is unique.  That is, a specific amount of "dipole moment" produces the dipole part of the field, a specific amount of "quadrupole moment" produces the quadrupole part, and so on.

Raiders of the Lost Energy
Now we can specify Dalrymple's second claim.  Referring to the report (MacDonald and Gunst, 1967) Barnes was publicizing, Dalrymple wrote:

"The same observatory measurements that show the dipole moment has decreased since 1829 also show that this decrease has been almost completely balanced by a corresponding increase in the strength of the nondipole field, so that the strength of the total observed field has remained about constant." (Dalrymple, 1983b, p. 3036)

Dalrymple's use of the word "strength" above is ambiguous.  If he meant "strength of the nondipole field" to mean the various non-dipole moments, then it is not clear how to compare them to the dipole moment or each other.  Magnetic moments (dipole, quadrupole, octopole, etc.) have different physical units (ampere-meters², ampere-meters³, ampere-meters⁴, etc.), so comparing them is like comparing apples and oranges.  The same confusion afflicts his phrase "strength of the total observed field."  If he meant "magnetic field intensity" (called B), that quantity varies from place to place and day to day.  However, Dalrymple is not a physicist, so it may be unreasonable to expect him to use physics terms precisely.  The context of his quote above is "energy", and if we use that word in his statement, we get a physically meaningful claim:

"...the decrease [of energy in the dipole part] has been almost completely balanced by a corresponding increase in the [energy] of the nondipole field, so that the [energy] of the total observed field has remained about constant."

This is consistent with the general thrust of Dalrymple's argument.  He appeared to be claiming that energy lost from the dipole part was not being dissipated as heat but being stored up in the non-dipole part.  Later, he hoped, the stored energy would be converted back into a dipole field of reversed direction, as strong as before.  That way, the field might maintain its energy through reversed and normal cycles for billions of years.  As far as I know, the skeptics have not clarified Dalrymple's ambiguity, but they appear to be intuitively interpreting it the way I have.

Better Data Since 1970
Barnes answered Dalrymple by dismissing the non-dipole part of the field as "noise" (Barnes, 1984).  While that statement incorrectly ascribes unreality to the non-dipole part of the field, it correctly implies that the non-dipole fields had not been measured very accurately up to that time.  Dalrymple had based his second claim on a recent increase in the non-dipole energy [McDonald and Gunst, 1967, p. 28, Fig 3(e)].  However, the increase was small compared to the scatter in the data points.  To estimate energies, the non-dipole parts need to be more accurately measured than the dipole parts (Humphreys, 2002).  The 1967 data were simply not good enough to support Dalrymple's point.

However, shortly after 1967, the non-dipole measurements began to get better.  The International Association of Geomagnetism and Aeronomy (IAGA) organized a systematic global effort to gather and publish more accurate data on the earth's magnetic field.  In 1970 they published the International Geomagnetic Reference Field (IGRF), a table of 129 numbers describing the dipole and non-dipole parts of the field that year.  Every five years since then, they have published more tables.  The whole set of 903 IGRF numbers from the years 1970 to 2000 are the most definitive description we can get of the earth's magnetic field and the changes in it (Mandea et al., 2000).

The Results:  Good News for Creationists
Last year, spurred by not-infrequent questions on the issue, I downloaded the IGRF website data and began turning the mathematical crank to determine the amount of energy in the dipole and non-dipole parts for each year.  The details are in my Creation Research Society Quarterly technical article (Humphreys, 2002), which should be preprinted on the Society's website soon.  The bottom line is that from 1970 to 2000, the dipole part steadily lost 235 ± 5 billion megajoules of energy, while the non-dipole part gained only 129 ± 8 billion megajoules.  Over that 30-year period, the net loss of energy from all parts was 1.41 ± 0.16 %.  At that rate, the field would lose half its energy every 1465 ± 166 years.  That high rate implies the field is young.

You may be wondering something about the non-dipole energy: even though its increase was not enough to account for the dipole energy loss, why should it increase at all?  The increase is an expected consequence of my theory of reversals and fluctuations (Humphreys, 1990, p. 137).  Small swirls and eddies of fluid flow in the core should carve small loops of electric current away from the main loop, as Fig. 4 suggests.  That would remove energy from the dipole part of the field and add it to the non-dipole parts.

However, the small current loops would lose energy faster than the larger loops.  The reason is that the decay time of a current loop is proportional to the square of its diameter (Humphreys, 1986, p. 119).  The non-dipole parts of the field lose their energy as heat faster than energy in the dipole part.

Interestingly, the paper Dalrymple cited agrees with me.  It commented that fluid motions drive the dipole energy "destructively" into the non-dipole part, causing a higher rate of energy loss as heat (MacDonald and Gunst, 1967, p. 25).  Dalrymple seems to have overlooked that comment, since it casts doubt on his hope that the non-dipole energy would be preserved.

As long as the dipole field is strong enough, it will give more energy to the non-dipole part than the latter dissipates as heat.  During that time the energy in the non-dipole part should indeed increase.  Eventually, however, when the dipole component gets small enough, it will not be able give enough energy to the non-dipole part to compensate for the losses therein.  Then, according to the theory, even the non-dipole energy will start decreasing.

At all times, however, the sum of the energies in both parts should decrease — as we see it doing today.  Dalrymple's hope is dashed.  Barnes was right.

A Tribute to Thomas G. Barnes
Last year Dr. Barnes went into the presence of his Creator and Savior, after a long and fruitful life of service in creation science.  It is entirely fitting that these data gathered in the last thirty years should vindicate the insight he had back in the early 1970's: that the earth's magnetic field is as young as the Bible says it is.

References

CRSQ: Creation Research Society Quarterly

Barnes, Thomas G. 1971. Decay of the earth's magnetic field and the geochronological implications. CRSQ 8:24–29.

1973. Electromagnetics of the earth's field and evaluation of electric conductivity, current, and joule heating in the earth's core. CRSQ 9:222–230.

1984. Earth's young magnetic age: an answer to Dalrymple. CRSQ 21:109–113.

Coe, Robert S., and Michel Prévot. 1989. Evidence supporting extremely rapid field variation during a geomagnetic reversal, Earth and Planetary Science Letters 92(3/4): 292–298.

Coe, R. S., M. Prévot, and P. Camps. 1995. New evidence for extraordinarily rapid change of the geomagnetic field during a reversal. Nature 374:687–692.

Dalrymple, G. Brent. 1983a. Can the earth be dated from decay of its magnetic field? Journal of Geological Education 31:121–133.

1983b. Radiometric dating and the age of the earth: a reply to scientific creationism, Proceedings of the Federation of American Societies for Experimental Biology 42:3033–3035.

Humphreys, D. R. 1986. Reversals of the earth's magnetic field during the Genesis Flood. In Walsh, R. E. (editor), Proceedings of the First International Conference on Creationism, Volume II, pp. 113-126. Creation Science Fellowship, Pittsburgh, PA.

1988. Has the earth's magnetic field ever flipped? CRSQ 25(3): 130-137.

1990. Physical mechanism for reversals of the earth's magnetic field during the Flood. In Walsh, R. E. (editor), Proceedings of the Second International Conference on Creationism, Volume II, pp. 129-142. Creation Science Fellowship, Pittsburgh, PA.

2002. The earth's magnetic field is still losing energy. CRSQ, in press. Preprint available from the Creation Research Society website: www.creationresearch.org.

Mandea, M., S. Macmillan, T. Bondar, V. Golokov, B. Langlais, F. Lowes, N. Olsen, J. Quinn, and T. Sabaka. 2000. International Geomagnetic Reference Field 2000. Physics of the Earth and Planetary Interiors 120:39-42. Data can be downloaded from the National Geophysical Data Center web site at www.ngdc.noaa.gov .

McDonald, Keith L. and Robert H. Gunst. 1967. An analysis of the earth's magnetic field from 1835 to 1965. ESSA Technical Report IER 4 6 –IES 1, U.S. Government Printing Office, Washington, D.C.

* D. Russell Humphreys is an Associate Professor of Physics for the Institute for Creation Research, PO Box 2667, El Cajon, California 92021: www.ICR.org.   He recently retired from Sandia National Laboratories in Albuquerque, NM.  This article was published in the March 31, 2002 issue of Creation Matters and is reprinted, in part, with the permission of CRSQ: www.CreationResearchSociety.org.

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